Cyclopropenoid fatty acids (CPFA) which occur in certain foodstuffs such as cottonseed oil and flour, kapok oil and okra are known to have toxic effects when consumed by animals. These unique compounds are known to impair reproduction in rats and chickens, alter the fatty acid composition in the body lipids of several species, and cause characteristic alterations in trout and rabbit liver parenchymal cells. In addition, our studies have demonstrated that CPFA act as powerful cocarcinogens with aflatoxin B1 and as carcinogens in the induction of liver cancer in rainbow trout. Cyclopropenes are postulated to bind with proteins and enzymes through a non-reversible reaction with the free sulfhydryls. A mechanistic study of the cyclopropene-sulfhydryl reaction will confirm or refute this theory. The lipid soluble metabolites will be isolated and identified. The toxicity of the major urinary metabolite will be determined. The goal of this research is to provide understanding and insight into the mechanisms of induction and promotion of cancer and concomitant physiological effects seen with dietary CPFA. A thorough understanding of these mechanisms will help to explain the different species responses to CPFA and will provide information relative to their potential health hazard to man.